1. Field of the Invention
This invention relates generally to head suspension assemblies for supporting a slider relative to a disk drive, and more particularly to suspension assemblies having motion limiters.
2. Description of Related Art
Storage devices typically include a head for reading and/or writing data onto a storage medium, such as a disk within a disk drive. An actuator mechanism is used for positioning the head at specific locations or tracks in accordance with the disk drive usage. Linear and rotary actuators are known based on the manner of movement of the head. Suspension assemblies are provided between the actuator and the head and support the head in proper orientation relative to the disk surface. In certain disk drives, suspension assemblies support a head to xe2x80x9cflyxe2x80x9d over the surface of the disk when it is spinning. Specifically, the head is typically located on a slider having an aerodynamic design so that the slider flies on an air bearing generated by the spinning disk. In order to establish the fly height, the suspension assembly is also provided with a spring force counteracting the aerodynamic lift force.
A suspension assembly of the type used in a disk drive comprises a load beam supporting the slider. Load beams normally have an actuator mounting portion, a rigid region, a spring region between the actuator mounting region and the rigid region for providing the aforementioned spring force, and a flexure at an end of the load beam distal from the actuator mounting portion to which the slider is mounted and which permits pitch and roll movements of the slider to follow disk surface fluctuations. Many types of flexures have been developed including flexures that are integrated into the design of the load beam and those formed as a separate element and fixed to the rigid region of the load beam.
In order to permit pitch and roll movements, flexures typically include a cantilever portion having a free end, which is resiliently movable relative to the remainder of the flexure. The flexure assembly allows gimballing of the slider/magnetic head combination. In some cases, the load beam includes a load portion that interacts with the flexure to provide a point load, such as by way of a dimple, to the flexure about which pitch and roll movements can occur.
In another type of suspension assembly developed by International Business Machines Corporation, the gimbal is integrated into the flexure. A pivot point such as a dimple is not relied upon for gimballing. An integrated or built-in gimbal structure comprising connecting portions or bridges that structurally couple a slider mounting base of the flexure to the load beam, defines axes of pitch and roll, and movements in other directions. This type of suspension is sometimes referred to as integrated gimbal suspension.
As disk drives are being designed with smaller disks, closer spacing, and increased storage densities, smaller and thinner suspension assemblies are required. These smaller and thinner suspension assemblies are more susceptible to be damaged if the disk drive is subjected to a shock load. Moreover, with increased disk storage density, it is necessary for the suspension assembly to hold the slider and head in flight very close to the disk surface, but to still permit pitch and roll movement. Thus, it is becoming increasingly more important to design the suspension assembly so that it is less susceptible to shock loads. Not only is it desirable to prevent damaging contact between the head slider and a disk surface, which could damage the slider and/or the disk surface, but also to prevent permanent deformation of any part of the suspension assembly as a result of a shock load. As flexures get smaller and thinner, there is a greater chance that a shock load could cause permanent deformation of the flexure even when the suspension assembly is parked outside of the disk surface when not in use, such as on a conventional comb structure. Limiters are therefore provided in suspension assemblies to restrict the range of movement of the free end of the cantilever portion of the flexure.
U.S. Pat. No. 5,771,136 provides a suspension assembly consisting of a flexure that is constructed as a separate element from the load beam. The flexure is gimbaled on a dimple that extends from the flexure and rests against the load beam. The slider is mounted in such a way that the slider gimbals about the dimple on the flexure. In this configuration in the presence of the dimple, the slider is allowed to only move in a direction generally away from the load beam; in other words, limiters provided outside of the gimbaled portion of the flexure further restrain the extent of motion in directions away from the load beam. The limiter configuration of the ""136 patent would not be appropriate for an integrated gimbal suspension since there is no dimple in the integrated gimbal suspension to constrain the slider. This ""136 patent would also fail for use in the integrated gimbal suspension because it provides only pitch, roll, and vertical movements in a direction normal to the slider.
There is a need to provide the necessary restraints for the flexure of the integrated gimbal suspension, preferably to limit motions in multi-degrees of freedom. It is therefore desirable to design a limiter that protects the slider from large displacement and damage and that overcomes the above-mentioned drawbacks.
The present invention is directed to a gimbal suspension that overcomes the shortcomings and disadvantages associated with the prior art integrated gimbal suspensions. In particular, the present invention is directed to an integrated gimbal suspension. However, it is understood that the present invention can be implemented generally to other types of suspensions without departing from the scope or spirit of the present invention.
The integrated gimbal assembly comprises a flexure with a built-in gimbal, and includes a limiter structure that constrains motions of the gimbal in multi-degrees of freedom, including translational (X, Y and Z), and rotational (yaw, pitch, and roll) motions of the slider. In accordance with one aspect of the present invention, the limiter structure includes one or more tab-shaped limiters and corresponding stops integrally formed into the gimbal assembly at strategic locations, which interact to provide the desired constraints to the motions of the flexure gimbal to prevent permanent damage from over-straining the gimbal or flexure beyond its designed range. The limiters may be pre-formed tab-shaped structures that are bent from the plane of the flexure (e.g., upwards and downwards as referenced to the plane of the flexure). As the gimbal moves from its nominal position (e.g., where there is no deflection of the gimbal with respect to the plane of the flexure), one or more limiters engage the corresponding stops before such motion reaches the limit of the designed range of motion of the gimbal.
In accordance with another aspect of the present invention, an integrated gimbal suspension is formed at one end of the flexure, which comprises an inner frame and an outer frame, and a number of connecting portions or bridges (crosspiece), which cantilever a mounting base on which a slider is mounted. The inner frame and/or the slider mounting base may xe2x80x9cpivotxe2x80x9d or move out of plane in the Z direction with respect to the outer frame, resulting in Z-translational, pitch and/or roll motions of the slider. Associated with such motion, the inner frame may also move sideways along the X and Y directions with respect to the outer frame, resulting in X and Y-translational and/or yaw motions of the slider. The net effect is that the slider attached to the slider mounting base can pitch, roll, yaw and move in X, Y and Z directions, as supported on the flexure. The flexure in effect creates an integrated gimbal suspension in that the gimbal support is integrated into the flexure (as compared to a dimple type gimbal structure in which the gimbal is provided by an external dimple support or a dimple on the flexure acting against an external surface such as the load beam). The limiters may be tabs that extend from the inner frame, the outer frame and/or the mounting base. The stops may be positioned on the inner frame, the outer frame and/or the mounting base in opposition to limiters to constrain the motions of the gimbal.
According to one embodiment of the present invention, two L-shaped limiters extend from the same section (e.g., the inner frame) of the same flexure material, with one limiter bent up and the other bent down to limit the Z direction, pitch, and roll motion of the slider. According to a second embodiment of the present invention, two pairs of face-to-face, L-shaped limiters extend from different sections (e.g., the crosspiece and the slider mounting base) of the same flexure material, with two limiters bent up and two limiters bent down. According to a third embodiment of the present invention, two pairs of L-shaped limiters facing the same direction extend from the same section (e.g., the crosspiece) of the same flexure material, with two limiters bent up and two limiters bent down.
In accordance with another aspect of the present invention, an integrated gimbal suspension assembly has limiters not only for the Z direction, pitch, and roll motions but also for the X and Y directions and yaw motions. The slider on the integrated suspension can move in all directions. The limiters protect a large range of slider motions, including excessive slider motion during side impact or shock.
According to yet another embodiment of the present invention, two pairs of face-to-face, U-shaped limiters extend from the same section (e.g., the crosspiece) of the same flexure material, with two limiters bent up and two limiters bent down. According to another embodiment of the present invention, a limiter made up of two L-shaped tabs extends from the same section (e.g., the outer frame) of the same flexure material, with the entire limiter bent either up or down.
The limiting function of the integrated gimbal suspension assembly can be also implemented with different combinations of the above-mentioned embodiments. These limiter designs can be used for flexures that support sliders on both planar surfaces of the flexure. Since all limiter features are etched from the same flexure material, or integrated with the flexure, there is no assembly of separate parts required; in addition, design, structural, and assembly tolerances can be more easily achieved, thus increasing production yield and reducing production cost.